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Proceedings Paper

Ultraviolet detector materials and devices studied by femtosecond nonlinear optical techniques
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Paper Abstract

Femtosecond nonlinear optical techniques have been employed in the study of carrier dynamics and transport in UV detector materials. Visible femtosecond pulses derived from the signal beam of a 250 kHz regenerative amplifier-pumped optical parametric amplifier were frequency doubled to obtain pulses tunable from 250 nm to 375 nm. Time-resolved reflectivity experiments indicate that the room-temperature carrier lifetime in GaN grown by double lateral epitaxial overgrowth is about 3 times longer than that of GaN grown on sapphire without benefit of this technique. The electron velocity-field characteristics and saturation velocity in GaN have been obtained form time-resolved studies of electroabsorption in a GaN p-i-n diode. The peak steady- state velocity of 1.9 X 107 cm/s in this device occurs at 225 kV/cm. Time-resolved transmission measurements have been used to monitor ultrafast carrier relaxation phenomena in a thin AlGaN layer with bandgap in the solar blind region of the spectrum. Excitation intensity and wavelength dependent studies of the photoinduced bleaching decays suggest that they are primarily governed by trapping in a high density of sub-bandgap defect levels.

Paper Details

Date Published: 13 April 2000
PDF: 11 pages
Proc. SPIE 3948, Photodetectors: Materials and Devices V, (13 April 2000); doi: 10.1117/12.382137
Show Author Affiliations
Michael Wraback, U.S. Army Research Lab. (United States)
Hongen Shen, U.S. Army Research Lab. (United States)
Patrick Kung, Northwestern Univ. (United States)
Manijeh Razeghi, Northwestern Univ. (United States)
John C. Carrano, West Point Military Academy (United States)
Ting Li, Univ. of Texas/Austin (United States)
Joe C. Campbell, Univ. of Texas/Austin (United States)

Published in SPIE Proceedings Vol. 3948:
Photodetectors: Materials and Devices V
Gail J. Brown; Manijeh Razeghi, Editor(s)

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